Polycrystalline material with a sharp superconducting transition at 39K was directly synthesized from the elements by using high pressure. The sample exhibited high critical current densities. The electron energy-loss spectrum of B showed the peaks of σ and anti-bonding bonds, in good agreement with hole-doping theoretical calculations. The pressure dependences of the sound velocities were measured at up to 0.5GPa and, from these, the elastic moduli (figure 13), Debye temperature and specific heat were calculated. The isothermal Murnaghan equation of state was established. The pressure coefficient of the phonon frequency and the volume dependence of the electron–phonon coupling constant were also calculated.

Property Studies of MgB2 Superconductor Directly Synthesized using High Pressure. C.Q.Jin, S.C.Li, R.C.Yu, F.Y.Li, R.J.Wang, J.L.Zhu, Z.X.Liu, L.C.Chen: Journal of Physics - Condensed Matter, 2002, 14, 10771-8